A randomized clinical trial in vitamin D-deficient adults comparing replenishment with oral vitamin D3 with narrow-band UV type B light: effects on cholesterol and the transcriptional profiles of skin and blood

Background: Vitamin D deficiency, defined as a serum 25-hydroxy-vitamin D [25(OH) D] concentration,20 ng/mL, is correlated with a more atherogenic lipid profile. However, oral vitamin D supplementation does not lower LDL-cholesterol concentrations or raise HDL-cholesterol concentrations. This uncoupling between association and causation may result from a failure of oral vitamin D to mimic the effect of dermally synthesized vitamin D in response to ultraviolet type B (UVB) light. Objective: We tested the hypothesis that, in vitamin D-deficient adults, the replenishment of vitamin D with UVB exposure would lower LDL-cholesterol concentrations compared with the effect of oral vitamin D-3 supplementation. Design: We performed a randomized clinical trial in vitamin D-deficient adults and compared vitamin D replenishment between subjects who received oral vitamin D-3 (n = 60) and those who received narrow-band UVB exposure (n = 58) <= 6 mo. Results: There was no difference in the change from baseline LDL-cholesterol concentrations between oral vitamin D-3 and UVB groups (difference in median of oral vitamin D-3 minus that of UVB: 1.5 mg/dL; 95% CI: -5.0, 7.0 mg/dL). There were also no differences within groups or between groups for changes in total or HDL cholesterol or triglycerides. Transcriptional profiling of skin and blood, however, revealed significant upregulation of immune pathway signaling with oral vitamin D-3 but significant downregulation with UVB. Conclusions: Correcting vitamin D deficiency with either oral vitamin D-3 or UVB does not improve the lipid profile. Beyond cholesterol, these 2 modalities of raising 25(OH) D have disparate effects on gene transcription.